In general, a water pump motor is used to drive a water pump that is installed in a drain water tank or is used as a driving source of a water pump that is used for circulation of a coolant that cools an engine. The water pump equipped with the water pump motor works under an environment that the inside of the water pump always directly contacts water.
Thus, a component that is called a mechanical seal is used in a water pump for sealing purposes in order to protect a motor from water when the water of the inside of the water pump is drained to the outside of the water pump or in order to prevent failure of bearings or shortened life of belts due to leakage of a coolant.
A conventional water pump that uses a mechanical seal requires a separate additional post-processing work in order to have the mechanical seal. Accordingly, a processing cost and a material cost for the mechanical seal rise up to thereby become a factor of raising the prime cost of the water pump using a water pump motor. In addition, water or foreign matters flowing from the outside of the water pump may be introduced into the water pump motor, to thereby cause breakdown of the motor.
A bearing structure for a water pump motor having a can cover in order to protect the water pump motor was disclosed in the U.S. Pat. No. 4,277,115. In the U.S. Pat. No. 4,277,115, a mount for calotte bearings in which a ring of an elastomer or of felt is disposed between the calotte bearing and a bearing support element and the calotte bearing and the bearing support element are provided with grooves in the region of this ring. The calotte bearing mount is particularly useful in pumps with canned motors for delivery of electrolyte liquid in fuel cell units.
In the above-described water pump having the can cover, water introduced into the water pump motor can be prevented to some extent. However, the can cover should be separately produced to be assembled with the motor, to thereby cause the prime cost of the water pump to rise and productivity to lower. Further, a waterproof structure for water entering from the outside of the water pump motor is not presented, to thus require for additional measures for waterproof.
Meanwhile, the water pump that is used for a washing machine may cause a phenomenon that foreign matters such as dirt and debris are introduced between an impeller and an upper housing and are attached onto the rear surface of the impeller, when the foreign matters separated from laundry are drained. This phenomenon may inhibit rotational movement of the impeller, and cause degradation of the motor.